EVM Sub-Protocol

The EVM sub-protocol defines how WalletPair sessions interact with EIP-155 compatible chains (Ethereum, Polygon, Arbitrum, Base, etc.). It is one of several sub-protocols that plug into the chain-agnostic core protocol.

Namespace: evm · Version: 1 · CAIP-2 prefix: eip155

All methods use the wallet_ prefix. Requests and responses are JSON objects encrypted end-to-end by the core protocol.

Methods

Method	Required	Description
`wallet_getAccounts`	Yes	Return authorized accounts. Must not prompt.
`wallet_signTransaction`	Yes	Sign a transaction without broadcasting. Returns signed RLP.
`wallet_sendTransaction`	No	Sign and broadcast. Optional — cold wallets omit this.
`wallet_signMessage`	Yes	EIP-191 personal sign. Not chain-bound.
`wallet_signTypedData`	Yes	EIP-712 structured data signature.
`wallet_switchChain`	Yes	Switch active chain. Must also emit `chainChanged`.
`wallet_addChain`	No	Add a new chain to wallet.
`wallet_watchAsset`	No	Track a token (ERC-20/721/1155).

Events

Event	Description
`accountsChanged`	Accounts list changed. Empty array = all access revoked.
`chainChanged`	Active chain changed.
`disconnect`	Wallet-initiated session end. Reasons: `user_closed`, `session_revoked`, `wallet_locked`.

Error Codes

Code	Meaning
`user_rejected`	User declined in wallet UI
`unauthorized`	Account not authorized for this session
`invalid_params`	Malformed or missing parameters
`unsupported_chain`	Chain not in capabilities
`unsupported_method`	Method not in capabilities
`insufficient_funds`	Balance too low
`nonce_too_low`	Nonce already used
`gas_estimation_failed`	Gas estimation reverted
`tx_rejected`	Network rejected the transaction
`internal_error`	Unexpected wallet error

Data Encoding

Data Type	Encoding
Addresses	`0x` + 40 hex chars (EIP-55 checksum)
Values, nonce, gas	`0x` hex string, no leading zeroes except `0x0`
Signed transactions	`0x` hex string (full RLP)
Signatures	`0x` hex string, 65 bytes (r + s + v)
Chain IDs (CAIP-2)	`eip155:<decimal>`
Chain IDs (tx)	`0x` hex